Buoyancy issues

Well, I'm showing my inexperience, but I'm sure you experts out there can help me.

I'm still a beginner.... been on about 15 dives. All my life I've been very buoyant, although I'm not sure why, as I'm not overweight by any means. (5'5"; 125 pounds; fairly even weight distribution

I've been using about 12 pounds of weight, which of course makes the other divers sneer. I don't put a lot of air in the BC, but some, of course. This is in tropical waters, with a lightweight shortie over a dive skin. (I get cold easily.)

While diving, I try to keep horizontal, with my feet a little higher than my head, because if I don't I am liable at any moment to just shoot upward, especially toward the end of the dive when we're not as deep and the tank is getting empty. But that position isn't always convenient or practical. Also, it's really really hard for me to do a slow ascent at the end of the dive, and staying steady for the safety stops is really tough.

I think next time I dive, I'll do a session just trying to get more comfortable with the buoyancy, but I'm sure someone out there has some great advice.

Thanks!

You really should re-check your weighting, as it sounds like you may not have enough. You shouldn't have to worry about shooting to the top towards the end of your dive. You should be neutral at the surface at the end of your dive with no air in your bc. The last thing you want to have to do is to fight to stay down, especially at your 15' safety stop.

Various factors will affect your buoyancy - natural body composition, your gear (esp. your exposure protection - the amount of neoprene you wear). Also keep in mind that towards the end of your dive, your tank will be more buoyant due to a lower amount of air in your tank. This means that if you are neutral at the surface before your dive, you will be positive by the end, which may explain why you may be having troubles controlling your ascent near the surface.

Find your proper buoyancy at the surface with a full tank, then add about 5 lbs to account for the buoyancy change.

While I'm surely no expert. I feel that the learning process "never" ends. You shouldn't feel anxious about the end of your dive and your weighting. That apprehension will make your breathing less than optimum and thus throw your buoyancy off more.

Get weighted at the surface with a new empty tank and use what weight you need, regardless of your physical weight or height. You might have hollow bones :wacko: just kidding! Horizontal is a better position wither your acscending or descending. I would stick to it if possible.

Never mind if other divers scoff at the amount of weight you're using.

Do the weighting routine as described above, and do it with an almost empty tank. Then add the abovementioned 5 lbs.

Account for added equipment, remember a dive light mostly means extra weight, but if you're diving with a buoyant specimen, you need to add weight to compensate.

Now, technique tips: on the surface, before descending, take a moment to relax all your muscles. Got it? Now: clench your abdominal muscles while keeping the rest of your body relaxed. You'll go down smoothly.

Underwater, keep relaxed. Let your BC carry you and never try to keep at a given level by finning. If you do this, you're not neutrally buoyant.

Try diving with steel tanks instead of aluminium tanks. There's not really a marked difference in weight, but steel tanks don't get as buoyant as aluminium tanks at the end of a dive.

Have someone check your BC underwater. Ask your buddy to check (feel) if the BC is really empty when you think it is during a dive (use a distinctive signal to ask him/her). Some types of BC have nooks and crannies that trap air.

Lastly and most importantly : take a buoyancy class. It'll cut your learning process by at least 10-20 dives.


BTW ABQdiver, maybe love2godeep really has light bones. I know I've got heavy, dense bones. Hence my party trick: I can sink to the bottom of the pool wearing a 2.5 mm shorty and holding a full breath. No weights of course.

Have fun, dive safe.

Not sure I understand what you mean by "I don't put much air into my BCD, but a little, of course".
When exactly do you put the air in? I only add air to my BC if otherwise I would be sinking (unless I want to sink, of course), but you seem to be buoyant most of the time on the dive, anyway. So while you probably are underweighted and should simply try with another kilo, you should also make sure that your BC does does not contain any unnessary air...

As pointed by others, you seem to be too buoyant. But consider this: your position in the water column (trim) will affect your buoyancy.

As an example: moa. I'm always horizontal. But when my legs are half flexed, I'm neutral. If I extend them and slightly head up, I'll ascend when I inhale. Likewise, if I exhale and flex my legs more, I'll descend.

3 other possible causes to your ordeal:

1. You're underweight
2. You don't release enough of the air that expands in your BC as you ascend
3. You need to learn a better way to use your lungs. They're your very own personal BC/ballast.

You need to play with this and find it out for yourself. It's important that you work on this sooner rather than later as rapid ascent is probably the worst situation when diving.

FatCat once bubbled...
Now: clench your abdominal muscles while keeping the rest of your body relaxed. You'll go down smoothly.

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Lots of good advice in this post, but what's with clenching the abdominal muscles? Muscle tone shouldn't affect buoyancy. Are you sure you're not just forcing continued exhalation here??

Jim

Fact # 1 Some people float.
Fact # 2 Some people are neutrally buoyant
Fact # 3 Some people sink.

I'm a floater, always have been. However, I have learned to control my breathing and have mastered a full-blown blue faced exhale with ease. I now dive with less weight than any of my dive buddies. It takes time, practice, and patients. But you will master your buoyancy control if you focus on it during every dive. Soon though it will become second nature and you will no longer have to "focus" on your buoyancy.

Being a "floater" has its advantages, for example; during the Dive Master program, one skill you need to demonstrate is "drown proofing". Simply put you have to tread water but not swim, for 15 minutes. The last 3 minutes you need to raise your hands out of the water in order to get a top score (5). Being a floater, all I did was float on my back for 12 minutes, then raise my hands for the last 3. I almost fell asleep! Body weight/size has absolutely nothing to do with whether you are a floater or a sinker, or nearly neutral. I have seen very large people (obese) who sink like a stone, and very fit body builder types who float like little islands, and I have seen the opposite as well.

So take what your genetic makeup has given you and make the best of it. Your just starting out in a sport in which the only score keeper is you, so have fun and explore.

GoBlue! once bubbled...


Lots of good advice in this post, but what's with clenching the abdominal muscles? Muscle tone shouldn't affect buoyancy. Are you sure you're not just forcing continued exhalation here??

Jim

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3 issues here :

First: contracted muscles take up less space than decontracted muscles. Mass doesn't change, volume (density) does. Usually this is compensated in the body by other muscles decontracting which doesn't change overall body volume. In the case of the abdominal muscles, no other muscles decontract (if the exercise is done right). Body volume will decrease a little, though admittedly not all that much. Body mass will of course stay the same.

Which brings us to the second issue: buoyancy and involuntary movement. A diver incapable of relaxing the body will move arms and legs, generating an overall upward propulsion on descent and a rigid body affects the position in the water column...

Leading us directly to issue #3: trim. A relaxed diver will assume an optimal position if weighted right and if the tank is positioned right. The way to go is to let yourself hang from your BC, trimming yourself the way an airline pilot trims an aeroplane: Feet up, feet down, hang left, hang right and so on.

This even gives you some propulsion due to the laws of hydrodynamics and the inertia principle. It's all about energy conservation.

Yours truly,

the Cat

FatCat once bubbled...
Never mind if other divers scoff at the amount of weight you're using.

Do the weighting routine as described above, and do it with an almost empty tank. Then add the abovementioned 5 lbs.

Account for added equipment, remember a dive light mostly means extra weight, but if you're diving with a buoyant specimen, you need to add weight to compensate.

...

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Add 5 pounds after getting neutral just beneath surface with an empty BC and near-empty tank! You've missed the point, Fat Cat!

The added 5 pounds is needed if one weights oneself just beneath the surface with an empty BC and A FULL TANK.

As for added equipment, one should be weighting oneself with all gear carried on a dive. Aside from some of the large battery packs carried by cave divers, dive lights aren't big factors in buoyancy; wet/dry suits are the biggest variable. For example, my full 1/4-inch wet suit requires about an additional 15 pounds of lead more than skins. On the other hand, my Polartec shortie requires none.